2009, in theaters

I've read the book.  Chris, with whom I saw the movie, has not (at least, as of press time).

First off, let me emphasize that this is not a kids' movie.  Yes, it was based on the graphic novel, but that's not a kids' books, either.  There is violence, sex, sexual violence, lots of murder, bad language, bad music, and a moral ambiguity that never takes a break.  If your 8-year-old can handle that, awesome.  If not, don't blame me; I warned you.  But it's rated R for a very good reason.  This is not one of those movies where they add the s-word to get a PG bumped up to a PG-13 and attract the 18-35 crowd.  This is a real, actual R movie.

OK, that's out of the way.

So, having said all that, I want to add that for the most part, I really did enjoy the movie. I never expected it to be exactly the same as the book.  For one thing, I was spoiled as to the ending.  For another, the book is long, and even with the movie as long as it is (162 minutes), something had to give.

I did find that having read the book filled in some blanks.  There were a few moments  that were a little unclear to Chris that made sense to me since I had the context.   So on the off chance you haven't heard already, the film takes place in a world where superheroes -- or, at least, costumed vigilantes -- are very real.  And illegal. Former heroes essentially have three paths they can take.  They can work for the government, like The Comedian.  They can flagrantly break the law, like Rorschach.  Or, they can retire, and either capitalize off their past, like Ozymandias, or just walk away from the whole thing, like Nite Owl.   But then, costumed heroes start turning up dead, leaving those who survive to face their demons and avenge their colleagues.

And by the way?  It's 1985 and the United States is counting down to nuclear war with the Soviet Union.

We open with a great montage that explains the alternate timeline we're dealing with, showing the heroes who have gone before; some are dead, others are retired.

As we proceed through the narrative line, we begin to fill in the blanks and learn more about the characters and what makes them tick.  Why is Silk Spectre so angry at her mother?  How did Dr. Manhattan gain superpowers (he's the only one who actually has them)?  What makes a hero?  What makes a villain?

I mentioned above that something had to give.  In the original text, much more attention is given to the backstories of the first generation of heroes.  This is not strictly necessary -- the opening scene really covers the major points -- but it does provide a lot of information.  Likewise, there is quote a bit more information about Ozymandias's post-hero activities -- he's a massively powerful businessman (it would not surprise me if it turned out he was a partial inspiration for David Xanatos).  Finally, there's a complex subplot invlving a man who runs an newsstand and a boy who buys comics there, which revolves around a comic within the comic (which is available on a direct-to-video DVD and will be a feature when the movie comes out on video).

You can't stand violence, or you have a small bladder.  Reference my paragraph above about the R-rating, and if that's not a deal-breaker, make sure you can handle sitting through a film that's almost 3 hours long.  If so, get going.

I do recommend reading the book first, but you can get away with no doing so.  If you come out of the movie less-than-impressed, though, seriously consider returning to the source material, rather than assuming that since the film didn't do it for you, the book can't.

Beware of spoilers...
The real Doomsday Clock is currently set to 11:55 PM.  Interestingly, the real-life Doomsday Clock in 1985 was set closer to midnight than the one in Watchmen.
TelevisionWithoutPity's Moviefile writes about the world in which the movie takes place, and writes reviews both with and without spoilers, as part of its extensive coverage  of the movie.
Francesco Marciuliano at Francesco Explains it All was impressed by the movie, but didn't really enjoy it.
Dana Stevens at Slate explains what the big deal is.
Wil Wheaton waxes enthusiastic about the film.
A review at Selections From the Scrolls of the PlatinumWarlock notes that some of the more graphic scenes take things a touch too far.